1. Field of the Invention
The present invention relates to a printer and, more particularly, to a borderless printer which prints an image on a sheet of paper without leaving top and bottom margins thereon.
2. Description of the Related Art
There are a variety of printers which print image data on a sheet of paper. One such printer is a thermal transfer printer which uses a thermal transfer head for transferring image data with heat and an ink film located under the thermal transfer head so as to print an image on a sheet of paper placed under the ink film. Especially, for full color printing, a color thermal transfer printer is constructed to superposingly print three colors of yellow, magenta and cyan of a color-separated image. The image obtained by such a printer is as sharp as a snapshot produced using an ordinary camera, which is developed on a sheet of photographic paper.
The thermal transfer printer can be put into practical use in a variety of fields. For instance, it can be used to output an image from an image input apparatus such as a scanner, to realize a computer graphic image, or to output an image of an electron microscope taken by a video camera.
FIGS. 1A and 1B illustrate sheets of paper bearing an image printed by a conventional printer. In practice, the image might be printed on a sheet of paper leaving top/bottom margins 2 thereon as shown in FIG. 1A, or might be skewed as shown in FIG. 1B.
The cause for these problems, i.e., the paper margins remaining or the printed image being skewed on the paper sheet, can be explained as follows. For instance, in a drum-type printer as shown in FIG. 2, a clamp 9 is used to force a paper sheet 13 into contact with a drum 16, such that printing is not performed on the leading edge of the paper sheet 13 which is in contact with the drum 16 by the clamp 9.
The above structure, which is mechanically constructed such that the paper sheet 13 is in contact with drum 16 by the action of the clamp 9, is overly complicated so that malfunctioning is common, whereby skewed images are printed as in FIG. 1B. At the very least, the above structure leaves border margins on the paper sheet, which degrade the overall appearance of the printed image. In the worst case, the printing must be performed again and accordingly wastes paper sheets. Further, an image inputted from a scanner must be reduced or truncated before printing.